Data SIM Cards in Cardiff
Data-only SIM cards in Cardiff from £4/month on Three's 5G network. Ideal for tablets, dongles, MiFi and routers.
Silux Mobile delivers data SIMs to Cardiff and all of Cardiff free by Royal Mail Tracked 48. Pure data, no calls or texts to pay for — on Three's 5G/4G network, on a 30-day rolling plan or a 3 to 24-month contract.
Why Cardiff Chooses Silux Data SIMs
Delivered to Cardiff
Free Royal Mail Tracked 48 delivery (2–3 working days) anywhere in the UK including Cardiff and Cardiff.
Three 5G in Cardiff
Our SIMs use Three's 5G/4G network with strong coverage across Cardiff and surrounding areas.
From £5/Month
Cheaper than Lebara, Giffgaff and SMARTY — with 5G included. Roaming is an extra cost and varies by package.
Flexible Plans
Every plan starts from 1 month — SIM cards on 30-day rolling plans or 3 to 24-month contracts, and rolling monthly broadband.
The Silux Mobile Promise
No price increases
Your price is locked — no price rises during your contract, ever
Free upgrades
Upgrade your plan or SIM for free, any time
No credit checks
No credit checks on our SIM contracts
No hidden fees
No hidden fees, no price increases
Data SIM Plans — Delivered to Cardiff
Data-only SIMs on Three 5G. 30-day rolling or 3 to 24-month contracts.
Data Plus
30GB
£6/mo
- 30GB data
- Tablet & dongle ready
- 4G/5G
- 30-day or contract
Unlimited Data
Unlimited
£16/mo
- Unlimited data
- 5G speeds
- No throttling
- 30-day or contract
Three 5G Data Coverage in Cardiff
Three's 5G/4G network covers Cardiff and Cardiff with strong signal for tablets, dongles and mobile routers. Over 99% UK population coverage.
Check Your Cardiff PostcodeData SIM Cards in Cardiff — FAQs
What happens if I go over the fair usage policy in Cardiff?
It depends on the network. As of August 2026, Three is more flexible and lenient with its fair usage policy, and it is rare that we need to warn customers. Vodafone and O2 are much stricter: if you go over more than twice, you will be notified to monitor your usage.
What is the cheapest data SIM in Cardiff?
Silux Mobile offers some of the cheapest data SIMs available in Cardiff — from £5/month on Three, Vodafone, EE and O2, on a 30-day rolling plan or a 3 to 24-month contract, with free Royal Mail Tracked 48 delivery to Cardiff.
Does Three have good coverage in Cardiff?
Yes. Three's 4G and 5G network covers Cardiff and the surrounding Cardiff area with strong indoor and outdoor signal. Check your exact postcode at siluxmobile.co.uk/network-coverage.
Can I get a data SIM delivered to Cardiff?
Yes. Silux Mobile delivers to all Cardiff addresses free by Royal Mail Tracked 48 (2–3 working days). Faster delivery can be chosen at checkout.
Will my price increase mid-contract?
No. Silux Mobile never raises your price mid-contract — no annual or inflation-linked rises. The price you sign up at in Cardiff is the price you keep.
Do you run a credit check in Cardiff?
No. There are no credit checks on our SIM contracts, so anyone in Cardiff can join regardless of credit history.
Are prices in Cardiff inclusive of VAT?
Yes. No hidden fees — every price shown to customers in Cardiff is the price you pay, incl. VAT. No setup fees and no price increases.